1. Field of Invention
This invention relates to a sheet metal container component and more particularly to an improved method and apparatus for forming and a construction of a digitally openable container component such as an end closure that provides ready access to the liquid contents through displaceable panels which are opened by applying downward digital pressure immediately adjacent the opening panels to deflect a surface common to both deflectable bubble configurations causing fracture of a frangible web around the panels to form openings in the closure wall. This component satisfies commercial requirements dictated by ecological demands and safety considerations.
2. Description of the Prior Art
The metal can has gained widespread acceptance as a beverage container. In fact, in 1974 over 60 billion metal cans were produced to hold beer, soda and other liquids. Most of these metal beverage cans have been constructed with a severable tab to allow ready access to the contents without requiring the use of a can opener or other similar auxiliary tool. There are numerous examples of tab openings in the prior art including U.S. Pat. Nos. 3,291,336 and 3,411,470.
More recently, public opinion and legislation have been directed against the tear-away tab in an ecological attempt to eliminate the removable top litter. The removable tabs have sometimes been discarded indiscriminately by the ultimate consumers in picnic grounds, on public beaches, along roadways and in lakes or streams. Fish and other wildlife have apparently been lured to these shining tabs and may have been killed as a result of consuming them.
The ideal ecological closure member for a beverage container should have an opening means which can be easily fractured, preferably with relatively little digital pressure, and yet remain integrally attached to the metal container. Since the 1930's, opening panels have been known that are entirely cut from the container wall and held in place with a sealant. The bond between the sealant and the container wall is fractured by applying downward pressure with the thumb, while the opening panel folds over the thin metal to form an opening hinge, as disclosed in U.S. Pat. No. 2,176,898. See also U.S. Pat. No. 3,886,881. To provide adequate sealant to the cut line around the opening panel is a time consuming and expensive operation.
U.S. Urmston Pat. No. 3,929,251 discloses an improved ecological closure having at least one opening panel defined by a fracturable web with an integral deflectable portion adjacent the panel. Upon applying digital downward pressure against the deflectable portion, fracture of the web is induced to permit inward displacement of a separated opening panel. A novel feature of that container component is that the application of localized digital pressure immediately adjacent the rigid opening panel initiates fracture of the web around the panel. Other prior art disclosures of interest are contained in U.S. Pat. No. 3,730,381 and U.S. Pat. No. 3,902,627. Fracture of the score in those prior art devices is accomplished by applying pressure to the defined opening panel itself, usually with an auxiliary tool such as a coin or with the fingers. The prior art also discloses a raised zone on the can end requiring several deflections thereagainst to cause the residual metal to fail, as shown in U.S. Pat. No. 3,638,825. A convex tab which can be flexed into a concave position is disclosed in U.S. Pat. No. 3,779,417.
The provision of adjacent multiple opening panels is well known. For example, adjacent multiple openings are known for containers having circular rotor members on the closure. The openings have been formed either on the rotor member, as in U.S. Pat. No. 3,100,589, or on the container itself, as in U.S. Pat. No. 3,115,994. These multiple openings are formed to control the amount and type of dispensing action desired, as is used in the sifting action of an ordinary salt shaker. Prior art also discloses a metal container wall comprising an inner tinplate ply having a plurality of openings under a pealable strip, as in U.S. Pat. No. 3,318,495. This series of openings is formed for pouring as well as venting. Utilization of a series of openings rather than one large opening also aids in maintaining the adhesion of the pealable strip in cans having high internal pressures, by dispersing the pressure against the strip to a few small areas rather than one large area. Methods for scoring a container closure are disclosed in U.S. Pat. No. 3,688,718. Other prior art disclosures of interest relative to methods and tools for forming opening panels in sheet metal containers include the following U.S. Pat. Nos.: Geiger 3,362,569 and Punte 2,187,433.